CVE-2026-25835 identifies a vulnerability in the Mbed TLS library (prior to version 3.6.6) and the TF-PSA-Crypto library (prior to version 1.1.0) related to improper handling of seeds in their Pseudo-Random Number Generators (PRNGs). PRNGs are fundamental components in cryptographic systems, generating random values used for key generation, nonces, salts, and other security-critical parameters. The misuse of seeds can degrade the entropy or predictability of the PRNG output, potentially allowing attackers to reproduce or predict random values. This undermines the confidentiality and integrity of cryptographic operations, such as TLS sessions, secure key storage, and authentication tokens. The vulnerability is particularly concerning in embedded and IoT environments where these libraries are widely deployed due to their lightweight design. Although no public exploits have been observed, the flaw represents a significant risk because it can facilitate cryptographic attacks like key recovery or session hijacking. The lack of a CVSS score indicates that the vulnerability is newly published and pending detailed assessment. The issue was reserved in early 2026 and published shortly thereafter, signaling recent discovery. The absence of patch links suggests that fixes may be forthcoming or in progress. Organizations relying on these libraries should monitor vendor advisories and prepare to apply updates promptly. Additionally, reviewing cryptographic usage and implementing defense-in-depth strategies can reduce risk exposure.

The misuse of seeds in the PRNG can severely impact the security of cryptographic operations, leading to potential exposure of sensitive data, unauthorized access, and compromised communications. For organizations worldwide, this vulnerability threatens the confidentiality and integrity of data protected by Mbed TLS and TF-PSA-Crypto, especially in embedded systems, IoT devices, and applications relying on these libraries for secure communications. Attackers exploiting this flaw could predict cryptographic keys or session tokens, enabling man-in-the-middle attacks, data decryption, or impersonation. The impact extends to industries such as telecommunications, healthcare, automotive, and critical infrastructure where embedded security is paramount. Given the widespread use of these libraries in constrained environments, the vulnerability could affect a broad range of devices, increasing the attack surface. The absence of known exploits reduces immediate risk but does not eliminate the potential for future attacks. Failure to address this vulnerability could result in significant operational disruptions, data breaches, and loss of trust.

1. Immediately monitor for official patches or updates from the maintainers of Mbed TLS and TF-PSA-Crypto and apply them as soon as they become available. 2. Conduct an inventory of all systems and devices using these libraries to identify affected versions. 3. Where patching is not immediately feasible, consider implementing compensating controls such as isolating vulnerable devices from critical networks or limiting their exposure. 4. Review cryptographic implementations to ensure proper use of randomness sources and consider integrating additional entropy sources if possible. 5. Employ runtime monitoring and anomaly detection to identify suspicious cryptographic behavior or unexpected network activity. 6. Engage with vendors and suppliers to confirm their remediation plans and timelines. 7. For new developments, adopt cryptographic libraries with proven secure PRNG implementations and maintain regular update cycles. 8. Educate development and security teams about the importance of secure random number generation and the risks of seed misuse. 9. Perform penetration testing focused on cryptographic weaknesses to validate the effectiveness of mitigations.